The electric double layer capacitor is a device produced based on a principle in which positive and negative surfaces of polarized electrodes physically adsorb anion and cation of electrolyte for storing electric energy.
One concrete construction of such capacitor is described in for example after-mentioned Patent Document-1 is that shows a conventional bipolar type electric double layer capacitor (which will be called just as capacitor hereinafter). The capacitor of Patent Document-1 has the following construction. That is, a plurality of cells are stacked on one another. Each cell comprises two collecting plates each having one surface to which an activated carbon electrode is bonded, a gel-electrolyte film or separator put between the two collecting plates to constitute a unit, and a laminated sealing packing member put around the unit to constitute the cell. A unit of the stacked cells is tightly put between two end plates to constitute the capacitor that has a sealed construction. The capacitor uses two thin and flexible metal plates as collecting terminals. Each collecting terminal is put between one of the end plates and the corresponding collecting plate achieving electric connection of the collecting terminal with the collecting plate. The collecting terminals have respective portions that project to the outside of the capacitor keeping the sealed construction.
In a conventional capacitor described in after-mentioned Patent Document-2, for obtaining a sealed and hermetical construction, an aluminum laminate film is used as a cover member of the capacitor. By applying certain heat to the aluminum laminate film, the film is softened and intimately attached to an outer surface of the capacitor to constitute the sealed and hermetical construction of the capacitor. In this capacitor, thin aluminum films are used as collecting metals that serve also as collecting terminals. Each collecting metal protrudes to the outside of the capacitor along an inner surface of the corresponding aluminum laminate film, and a protruded portion of the collecting metal and the aluminum laminate film are subjected to a so-called heat seal process. With this, the collecting metals are protruded to the outside of the capacitor keeping the sealed construction.
Patent Document-1: Japanese Laid-open Patent Application (tokkai) 2003-217985
Patent Document-2: Japanese Laid-open Patent Application (tokkai) 2002-313677
Patent Document-3: Japanese Laid-open Patent Application (tokkai) 2006-024660